Polymerization of unsaturated compounds having the cyclopentadiene nucleus



' tributed catalyst and (4) time.

Patented Mar. 30, 1943 UNITED STATES PATENT'OFFICE,

POLYMERIZATION OF UNSATURATED COM- POUNDS HAVING THE CYCLOPENTADIENENUCLEUS Frank J. Soday, Upper Darby, Pa., assignor to The United GasImprovement Company, a corporation of Pennsylvania No Drawing.Application April 28, 1938, Serial No. 204,786

10 Claims.

chloride, and high flash naphtha, while the other 3 is characterized bybeing insoluble in these solvents.

The polymerization is usually carried out while the cyclopentadiene isin solution in a solvent.

I have discovered that the soluble type of polymer may be produced withaluminum chlorideorganic solvent complexes by a careful control of thepolymerizing reactiomwhereas this is not possible with aluminum chlorideitself.

Examples of aluminum chloride complexes are aluminum chloride-benzenecomplex, aluminum chloride-toluene complex, aluminum chloridepentenecomplex, aluminum chloride-decene complex, aluminum chloride-diethylether complex, aluminum chloride-phenyl methyl ether complex, aluminumchloride phenyl ethyl ether complex, and aluminum chloride-diisopropylether. complex.

The preparation of complexes of this character in general comprisesadding aluminum chloride to the solvent with agitation. As a result, ifa reaction takes place, a definite chemical compound is formed.

There are at least four factors which influence production of solublepolymer. These four factors are (1) temperature, (2) concentration ofcyclopentadiene, (3) proportion of uniformly dis- Generally speaking,and all other conditions remaining the same, it appears that there is athreshold temperature for the formation of insoluble polymer, and thatat all temperatures below this threshold temperature the soluble polymerresults. It is recognized, that high concentrations of cyclopentadieneand/or high proportions distributed catalyst a threshold temperature canbe shown to exist for any given concentration of cyclopentadiene withany given proportion of uniformly distributed catalyst.

Also generally speaking, and all other conditions remaining the same, itappears that there is a threshold concentration of cyclopentadiene forthe formation of insoluble polymer, and that at all concentrations belowthis threshold concentration the soluble form of polymer results. Theterm concentration of cyclopentadiene as used herein and in the claimsspecifies the percentage by weight of total cyclopentadiene,

whether reacted or not, after all of the materials have been combined.It is recognized that inordinately high temperatures and/ orinordinately high proportions of uniformly distributed catalyst may makethe theoretical threshold concentration diflicult of determination.However, for

reasonable temperatures and reasonable proportions of uniformlydistributed catalyst a threshold concentration of cyclopentadiene can beshown to exist at any given temperature with any given proportion ofuniformly distributed catalyst.

Also generally speaking, and all other conditions-remaining the same,and assuming that all of the materials have been combined, it appearsthat there is. a threshold proportion of uniformly distributed catalystfor the formation of insoluble polymer, and that with all proportionsbelow this threshold the soluble polymer results. *In this connectionexperiments indicate quite clearly that catalyst is apparently used upduring the polymerization of soluble polymer, and that additionalcatalyst is required to convert the soluble polymer into insolublepolymer. If the proportion of uniformly distributed catalyst is suchthat there is no catalyst available for the formation of insolublepolymer, none will be formed,

of uniformly distributed catalyst might place this theoretical thresholdtemperature below commercially obtainable temperature levels. However,for reasonable concentrations of cyclopentadiene and reasonableproportions of uniformly On the other hand, threshold proportions ofcatalyst are not required to polymerize all of the cyclopentadiene intothe soluble polymer, although it will be recognized that a minimumproportion will be required for maximum yields.

It is recognized that inordinately high temperatures and/or inordinatelyhigh concentrations of cyclopentadiene may make the theoreticalthreshold proportion of uniformly distributed catalyst difficult ofdetermination. However, for reasonable temperatures and reasonableconcentrations of cyclopentadiene a threshold proportion of uniformlydistributed catalyst can be shown to exist at any given temperature withany given concentration of cyclopentadiene.

Also-generally speaking, and all other condiaction time to approachinfinity.

tions remaining the same, it appears that there is a threshold reactiontime for the formation .of insluble polymer, and that for all reactiontimes below this threshold reaction time the soluble polymer results. Itis recognized that low tmperatures, low concentrations ofcyclopentadiene, and/or low proportions of uniformly distributedcatalyst may cause this theoretical threshold re- On therother hand hightemperatures, high, concentrations of cyclpentadiene and/or highproportions of uniformly distributed catalyst may cause this theoreticalthreshold reaction time to approach zero. However, for reasonabletemperatures, for reasonable concentrations of cyclopentadiene, and/orfor reasonable proportions of uniformly distributed catalyst, athreshold reaction time can be shown to exist.

Threshold reaction time, however, differs from the other three factorsin that when the threshold reaction time becomes more than one hour thetime necessary to form insoluble polymer approaches infinity at a veryrapid rate.

When threshold conditions are just exceeded insoluble polymer is formedbut not exclusively. This results in a mixture of soluble and insolublepolymer.

When exceeding threshold conditions to a greater extent, however,insoluble polymer is formed exclusively. The band over which bothsoluble and insoluble polymers are formed varies in width with change inconditions. For instance this band decreases in width with increase intemperature.

Furthermore, theexact values of (1) temperature, (2) concentration ofcyclopentadiene, (3) proportion of uniformly distributed catalyst and(4) time at which insoluble polymer begins to appear may vary somewhatwith change in purity or source of cyclopentadiene or of catalyst or ofsolvent or a change in catalyst or solvent. However, the exact valuesmay be readily determined by test.

The soluble polymer obtained varies in physical characteristics with thesolvent used during the polymerization. For instance solublepolycyclopentadienes obtained by polymerizing cyclopentadiene by my newprocess insolvent naphtha, toluene, or benzene difier somewhat from eachother as shown, for example, in the suitability of thesepolycyclopentadienes for coating metals for which they are unusuallywell suited. As an illustration, for certain purposes the benzenepolymer is superior, the toluene polymer coming next but being,nevertheless, particularly well suited.

Accordingly, in the preparation of my polymerized cyclopentadiene asolution of cyclopentadiene in a chosen solvent such as toluene isemployed.

I use as catalyst one or more aluminum chloride-organic solvent complex,and particularly one or more aluminum chloride-ether complex.

The complex catalysts are preferably employed in the form ofsuspensions, emulsions, or solu tions in organic solvents of whichbenzene, toluene, solvent naphtha and petroleum naphtha are examples.Such suspensions, emulsions, or solutions are formed by adding thecatalyst to the solvent followed by stirring. As an example, I find thata concentration of aluminum chloride complex in toluene of 1.0% byweight of. toluene is very suitable as a catalyst suspension althoughany other concentration or solvent suitable for the purpose may beemployed.

rapidly since under such circumstances the reaction may proceed tooviolently and cause local overheating with the production of insolublepolymer, or undesirable color bodies, or both, which it is proposed toavoid.

While the catalyst may be added to the solution of cyclopentadieneparticularly when the catalyst itself is in solution or in suspension ina solvent, I prefer to add the solution of cyclopentadiene to asuspension, emulsion or solution of thecatalyst. This affords a moreexact control of the amount and distribution of cyclopentadieneundergoing reaction at any one time. The reaction proceeds much moresmoothly than when the catalyst is added to the cyclopentadiene. In thelatter case no reaction appears to take place until a certain catalystconcentration is reached whereupon the reaction proceeds at a very highrate, and may get out of control.

In either event, however, the addition of one material to the other ispreferably accompanied by thorough stirring which is preferably rapid toinsure uniform distribution not only of the materials but also oftemperature.

In addition the reaction is preferably carried out in apparatus capableof temperature control such as a jacketed vessel provided with anagitator.

A very effective control of the temperature of the reactionand of localsuperheating is afforded when the preferred procedure is followed.

As an example, the proportion of catalyst may conveniently be between0.5% to 5.0% by weight of cyclopentadiene provided the temperature ofthe reaction is controlled and/or the concentration of cyclopentadieneis sufficiently low, thus avoiding the formation of insoluble polymer.

A proportion of catalyst of 1.0% by weight of the total cyclopentadienepresent is found to be very convenient. It permits wide variation intemperatures and in concentrations of cyclopentadiene without danger ofthe formation of insoluble polymer. Furthermore, there is lesslikelihood of discoloration of the final product than if a largerproportion of catalyst were used.

Incidentally, it appears that the molecular weight of the resultingsoluble polycyclopentadiene may be varied somewhat" by varying theproportion of catalyst. Other conditions remaining the same, higherproportions of catalyst yield polymers of higher molecular weight. Thisis very pronounced when the reaction temperature is 0 C. but is muchless pronounced at C.

For instance, at all temperatures below 50 C. gel-like polymers areobtained when high proportions of catalyst are employed just belowthreshold conditions. The ease with which gellike polymers are obtainedincreasees with decrease in temperature. These polymers are completelysoluble.

Incidentally, the formation of gel does not indicate definitely thepresence of insoluble polymer as shown above.

Discolorationof the product appears to increase and decrease withincrease and decrease in proportion of catalyst so that lowerproportions of catalyst yield materials of lesser discoloration.

Temperatures above 100 C. are preferably avoided and it is recommendedthat great care be taken to keep the temperatures throughout thereactionbelow this point.

It is found that temperatures between -40 C. to 70 C. are suitableprovided the reactants are sufilciently agitated or other steps taken toavoid local overheating. The preferred temperature range is between -40C. and 30 C.

Incidentally it appears that the molecular weight of the resultingsoluble polycyclopentadiene may be varied somewhat by varying thetemperature. Other conditions remaining the same, lower temperaturesyield materials of higher molecular weight. Furthermore, lowertemperatures yield materials of lesser discoloration.

The increase in color due to increased reaction temperature is quitenoticeable at 45 C. and becomes very pronounced as the reactiontemperature approaches 100 C.

On the other hand, at 'C. and even though the proportion of catalyst isfairly high, surprisingly light colored polymers are obtained.

Low reaction temperatures are therefore lncentration can be used,keeping in mind whatv has been said with respect to thresholdconditions, although I more often employ concentrations ofcyclopentadiene of from 20 to 30% by weight of total reactants.

Incidentally it appears that the molecular weight of the resultingsoluble polycyclopentadiene may be varied somewhat by varying theconcentration of cyclopentadiene in the starting material. Otherconditions remaining the same, higher concentrations of cyclopentadieneyield materials of higher molecular weight.

In summing up it may be said thathigher molecular weight polymer can bemade more advantageously at lower temperatures, with highercyclopentadiene concentrations, and with higher proportions of catalyst.

Under the recommended conditions the polymer is formed in good yield andwith a satisfactory color. p

The chosen time for the reaction may vary considerably keeping in mindwhat has been said about threshold conditions. I find that forpracticable purposes and good yields other conditions should be chosensuch that the reaction time is somewhere in the neighborhood of one houror more. This is borne out by thev fact that the yield increases withreaction time up to a certain point. The time is,of course, preferablychosen to obtain good yields.

The following specific examples will serve to further illustrate theinvention.

Example 1 0.30 cubic centimeter of aluminum chloride-diethyl ethercomplex is added to 60 grams of toluene with thorough agitation to forma suspension, emulsion or solution.

A mixture of 20 grams of cyclopentadiene and 20 grams of toluene areadded to the suspension during the course of'12 minutes, the temperatureranging'from 26-49 C. during the addition. The mixture is then agitatedfor an additional hour, after which 1 cubic centimeter of water isadded. This is followed by agitation for 15 minutes.

10 grams of quickline (CaO) are now added to the reaction mixturefollowed by agitation for an additional hour. Y

5 grams of a suitable filter aid are then added, and the mixturefiltered.

A filtered solution containing 16.4 grams of polycyclopentadiene is thusobtained.

Generally speaking, any other aluminum chlothat both the cyclopentadieneand the catalyst ride-organic solvent complex might be substituted.

In the above specific example it will be noted are in diluted formbefore addition. Furthermore,- as pointed out above dilutedcyclopentadiene is preferably added to diluted catalyst rather than viceverse to afford a better control of the speed and uniformity of thereaction and of the amount of heat evolved and consequently the type ofpolymer produced. The reaction runs smoother and is much more easilycontrolled on a large scale.

The addition of water to hydrolyze the catalyst makes it possible notonly to completely remove the activity of the catalyst and thus stop thereaction at any point, but also makes itpossible to remove the corrosiveand discoloring acid constituents of the catalyst by a suitable alkali.

The alkali is preferably added with the water used to hydrolyze thecatalyst, although it may be added later if desired. The failure tosubstantially completely remove the catalyst and its hydrolysis productsmay be the cause of serious discoloration. The insoluble reactionproducts formed during the hydrolysis and neutralization remain behindon the filter leaving a highly purified filtrate.

Example 2 1.60 cubic centimeters of aluminum chlorideof 1%; cubiccentimeters of 20% sodium carbonate solution and 1 /2 cubic centimetersof a 20% ammonium chloride solution is added. This is followed byagitation for one hour.

15 grams of quicklime (CaO) are now added to the reaction mixturefollowed by agitation for 16 hours.

10 grams of a suitable filter aid are then added and the mixturefiltered. I

A filtered solution containing 47.4 grams of polycyclopentadiene is thusobtained. The polycyclopentadiene has an average molecular weight ofabout 2000 as determined by the cryoscoplc method, using benzene as thesolvent.

Example 3 0.60 cubic centimeter of aluminum chloridediethyl ethercomplex is added to grams of benzene with thorough agitation to form asuspension, emulsion or solution.

A mixture of 60 grams of cyclopentadiene and 60 grams of benzene areadded to the suspension during the course of 7 minutes, the temperatureranging from 4 to 20 C. during the addition.

The mixture is then agitated for an additional period of 4 hours at atemperature ranging from 5 to 10 C., after which a mixture of 1 cubiccentimeters of 20% sodium carbonate solution and 1 cubic centimeters ofa 20% ammonium chloride solution is added, followed by the' addition of2 grams of solid sodium carbonate and 200 grams of benzene. This isfollowed by agitation for one hour. i

20 grams of quicklime (CaO) are now added to the reaction mixture,followed by agitation for one hour.

grams of a suitable filter aid are then added, and the mixtureflltered.a

A solution containing 45.0-grams of polycyclopentadiene is thusobtained.

The polymer may be used as such, or it may be concentrated in a vacuumstill of suitable design to give a product containing any desired higherconcentration of polycyclopentadiene in-' cluding solidpolycyclopentadiene, or it might be diluted to give any desired lowerconcentration,

or a second solvent might be substituted such as a higher boilingsolvent. This may be done either before or after concentration by addingthe second solvent and distilling.

In the above examplesthe particular temperatures were chosen to controlthe physical properties such as viscosity and color of the product.

It will be noted that at no time did the temperature exceed 100 C. oreven 70" C. The manner of combining the reactants, constant agitation,and brine cooling made it possible to prevent local overheating, and theformation of insoluble polymer.

In the above examples (1) temperature, (2) concentration ofcyclo-pentadiene, (3) proportion of uniformly distributed catalyst, and(4) reaction time may be varied considerably in the production ofsoluble polymer having in mind what has been said with respect tothreshold conditions. If it is found that insolubl polymer is obtained,one or more of the four conditions, namely 1) temperature, (2)concentration of cyclopentadiene, (3) proportion of catalyst, and (4)reaction time should be reduced until the soluble polymer is obtained.

Carrying out the polymerization in the presence of a solvent makes itpossible to have any desired concentration of cyclopentadiene.

While in the above example no dilution of the product was required tofacilitate hydrolysis and/or filtering, it is to be understood thatdilution with a solvent may be employed, if desired, particularly in thecase of highly viscous products.

Generally speaking, for the formation of soluble polymer to theexclusion of insoluble polymer and of extreme discoloration,temperatures should rarely exceed 100 C., and preferably should notexceed 70 0., concentrations of cyclopentadiene should rarely exceed 50%by weight of the total solution except possibly at low temperatures, andconcentrations of uniformly distributed catalyst should rarely exceed byweight of cyclopentadiene.

It should be kept in mind that there are for practical purposes minimumvalues for temperature, concentration of cyclopentadiene, proportion ofcatalyst and time, which practice will show ought to be exceeded toobtain reasonable yields. For instance, I find that when using ordinarycommercial toluene as the solvent at least 1.0 gram of aluminumchloride-ether complex per 100 grams cyclopentadiene is required. 0n theother hand, if the maximum values given in the previous paragraph fortemperature, catalyst and cyclopentadiene were used simultaneously,

tiveiy concentrated.

insoluble polymer would be formed, even though is used as apolymerization medium, it is to be understood that other suitablesolvents may be substituted of which benzene, xylene, ethyl benzene,solvent naphtha, petroleum naphtha, carbon tetrachloride, decaline,triethylbenzene and ethylene dichloride ar examples The products withbenzene and toluene are preferred for specific uses as hereinafterreferred to. Products with tetralin and pentene-2 are also very ood.

Although in the above particular description both reactants, namelycatalyst and unsaturated compound, are diluted prior to their admixture,it is to be understood that variations are possible. For instance, it isconceivable that all of the diluent may be first mixed with one of thereactants (either catalyst or unsaturated compound) and that the otherreactant may be added in concentrated form, particularly if theprinciples set forth herein are closely observed. Or the larger part ofthe diluent may be added to one of the reactants so that the other isrela- It is also conceivable that, withthe exercise of extrem care andthe closest adherence to the principles set forth herein, b'othreactants might possibly be employed in relatively concentrated form.Other variations are possible. When adding one liquid to another withagitation I find it convenient and often preferable to do this below thesurface of one of the liquids.

Any other suitable alkali such as sodium hydroxide, sodium carbonate,sodium bicarbonate, magnesium hydroxide, an amin or other basicsubstance might be substituted for quicklime in th above specificexamples, followed by a nonacidic drying agent such'as NazSO4, or sodalime. Both neutralization and drying is effected by Geo;

In case it is desired to form, a highly concentrated solution ofpolycyclopentadiene, or to isolate it in solid form, it is not necessaryto dry the solution after neutralization as the water present can bereadily removed in the subsequent concentrating operation. The completeremoval of insoluble material present, such as the neutralizing agent,is then efiected by filtering the partially concentrated solution afterthe complete removal of the water present by distillation. After thisstep the solution can be further concentrated if desired.

The product may be used for many purfoses, for instance for lacquersgenerally, for varnishes either alone or in admixture with other resins,for enamels, for paints, or in fact for coating compositions generally.It is ideally suited to the coating of metals, for instance, for thcoating of food containers as described and claimed in copendingapplication, Serial Number 291,007, filed August 19, 1939, by Newcomb K.Chaney. This is especially true of the products polymerized in benzeneand toluene.

If desired, it is possible to obtain soluble polycyclopentadiene ofhigher viscosity or of otherwise changed characteristics by startingwith a solution of polycyclopentadiene and stopping the reaction beforethreshold conditions are exceeded.

While the invention has been particularly described in connection withthe polymerization of cyclopentadiene, it is to be understood that it isapplicable to the polymerization of substituted cyclopentadienes havingthe cyclopentadiene nucleus containing the characteristic conjugateddouble bonds. However, it is to be understood that the polymerparticularly described has certain unique characteristics whichdistinguish it from polymers prepared from other starting materials.Examples of such other compounds are the, alkyl, aryl, and alkyl-aryl.

It is to be understood that the above specific .tion of a cyclic dienecompound selected from the class of cyclic dienes consisting ofcyclopentadiene, alkyl substituted cyclopentadiene and aryl substitutedcyclopentadiene in the substantial absence of polymerizable compoundsnot contained in said class, comprising mixing with said cyclic diene inthe presence of a solvent to effect said polymerization in considerableproportion to said cyclic diene polymer a hydrolyzable aluminumchloride-organic solvent complex previously formed by reacting aluminumchloride with an organic solvent capable of reacting with aluminumchloride to form said hydrolyzable complex; and preventing thepolymerization of said cyclic diene from being effected entirely tobenzene-insoluble cyclic diene polymer by thoroughly agitating thereaction mass while maintaining the reaction temperature below 100 C.,the concentration of said cyclic diene below 50% by weight, and theproportion of catalyst to said cyclic diene below 25% by weight, and bystopping the reaction by inactivating said catalyst whilebenzene-soluble cyclic diene polymer is present in the reaction mass.

2. A process for producing benzene-soluble cyclic diene polymer by thecatalytic polymerization of a cyclic diene compound selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl-substitutedcyclopentadiene and aryl substituted cyclopentadiene in the substantialabsence of polymerizable compounds not contained in said class,comprising mixing with said cyclic diene in the presence of a solvent toefiect said polymerization in. considerable proportion to said cyclicdiene polymer a hydrolyzable aluminum chloride-organic. solvent complexpreviously formed by reacting aluminum chloride with an organic solventcapable of reacting with aluminum chloride to form said hydrolyzablecomplex: and preventing the polymerization of said cyclic diene frombeing efiected largely to benzene-insoluble cyclic diene polymer bythoroughly agitating the reaction mass, while maintaining the reactiontemperature below 70 C., the concentration of said cyclic diene below50% by weight, and the proportion of catalyst to said cyclic diene below5% by weight, and by stopping the reaction by inactivating said catalystwhile benzene-soluble cyclic diene polymer isthe preponderant polymerpresent in the reaction mass.

3. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceof polymerizable compounds other than cyclic dienes selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene and aryl substituted cyclopentadiene, comprising mixingwith said cyclopentadiene in the presence of a solvent to eife'ct saidpolymerization in considerable proportion to polycyclopentadiene ahydrolyzable aluminum chloride-organic solvent complex previously formedby reacting aluminum chloride with an organic solvent capable ofreacting with aluminum chloride to form' said hydrolyzable complex; andpreventing the polymerization of said cyclopentadiene from beingefiected entirely to benzene-insoluble polycyclopentadiene by thoroughlyagitating thereaction mass while maintaining the reaction temperaturebelow 70 0., the concentration of said cyclopentadiene below 50% byweight, and the proportion of catalyst to said cyclopentadiene below 25%by weight, and by stopping the reaction by inactivating said catalystwhile benzene-soluble polycyclopentadiene is present in the reactionmass.

4. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymeriza solvent capable of reacting with aluminum chloridein a manner-to form said hydrolyzable complex, and preventing thepolymerization of said cyclopentadiene from being efiected largely tobenzene-insoluble polycyclopentadiene by thoroughly agitating thereaction mass while maintaining the reaction temperature below 70 C.,the

concentration of said cyclopentadiene below 50% by weight, and theproportion of catalyst to said cyclopentadiene below 5% by weight, andby stopping the reaction by inactivating said catalyst whilebenzene-soluble polycyclopentadiene is the predonderant polymer presentin the reaction mass.

5. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceof polymerizable compounds other than cyclic dienes selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene, and aryl substituted cyclopentadiene, comprising mixingwith said cyclopentadiene in the presence of a solvent to effect saidpolymerization in considerable proportion to polycyclopentadiene ahydrolyzable aluminum chloride-organic solvent complex, previouslyformed by reacting aluminum chloride with an organic solvent capable ofreacting with aluminum chloride to form said hydrolyzable complex; andsubstantially completely preventing the conversion of saidcyclopentadiene to benzene-insoluble polycyclopentadiene by thoroughlyagitating the reaction mass while maintaining the reaction temperaturebelow 70 C., the concentration of said cyclopentadiene below 50% byweight, and the proportion of catalyst to said cyclopentadiene below 5%by weight, and by stopping the reaction by inactivating said catalystbefore substantially any benzene-insoluble polycyclopentadiene ispresent in the reaction mass.

6. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceof polymerizable material other than cyclic dienes selected from theclass of cyclic dienes consistingof cyclopentadiene, alkyl substitutedcyclopenta-- diene and aryl substituted cyclopentadiene, comprisingdiluting said cyclopentadiene with a suitable solvent, diluting with asuitable solvent a hydrolyzable aluminum chloride-organic solventcomplex previously formed by reacting aluminum chloride with an organicsolvent capable of reacting V with aluminum chloride to form saidhydrolyzable complex, effecting said polymeriza tion in considerableproportion to polycyclopenta diene by slowly adding said solution ofcyclopentadiene to said diluted catalyst with thorough mixing whilemaintaining the reaction temperature below 70 C., the concentration ofsaid cyclopentadiene below 50% by weight, and the proportion'of catalystto said cyclopentadiene below by weight, and stopping the reaction byinactivating said catalyst before substantially any benzene-insolublepolycyclopentadiene is present in the reaction mass.

7. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization 01' cyclopentadiene in the substantial absenceof polymerizable compounds other than cyclic dienes selected from theclass of cyclic dienes consisting of cyclopentadiene, alkyl substitutedcyclopentadiene and aryl substituted cyclopentadiene, comprising mixingwith said cyclopentadiene in the presence of a solvent to effect saidpolymerization in considerable proportion to polycyclopentadiene ahydrolyzable aluminum chloride-ether complex previously formed byreacting aluminum chloride with an ether capable of reacting withaluminum chloride in a manner to form said hydrolyzable com plex; andpreventing the polymerization of said cyclopentadiene from beingeffected largely to benzene-insoluble polycyclopentadiene by thoroughlyagitating the reaction mass while maintaining the reaction temperaturebelow 70 C., the concentration of said cyclopentadiene below 50% byweight, and the proportion of catalyst to said cyclopentadiene below 25%by weight, and by stopping the reaction by inactivating said catalystwhile benzene-soluble polycyclopentadiene is the preponderant polymerpresent in the reaction mass.

,8. A process for producing benzene-soluble .polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceof all other compounds polymerizable under the conditions obtaining,comprising mixing with said cyclopentadiene in the presence of a solventto effect said polymerization in considerable proportion to'polycyclopentadiene a hydrolyzable aluminum chloride-organic solventcomplex previously formed by reacting aluminum chloride with an organicsolvent capable of reacting with aluminum chloride to form saidhydrolyzable complex; and preventing the polymerization of saidcyclopentadiene from being effected entirely to benzene-insolublepolycyclopentadiene by thoroughly agitating the reaction mass whilemaintaining the reaction temperature below C., the concentration of saidcyclopentadiene below 50% by weight, and the proportion of catalyst tosaid cyclopentadiene below 25% by weight, and by stopping the reactionby inactivating said catalyst while benzene-soluble polycyclopentadieneis present in the reaction mass,

9. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceof all other compounds'polymerizable under the conditions obtaining,comprising mixing with said cyclopentadiene in the presence of a solventto effect said polymerization in considerable proportion topolycyclopentadiene a hydrolyzable aluminum chloride-organic solventcomplex previously formed by reacting aluminum chloride with an organicsolvent capable of reactiong with aluminum chloride to form saidhydrolyzable complex; and preventing the polymerization of saidcyclopentadiene from being effected largely to benzene-insolublepolycyclopentadiene by thoroughly agitating the reaction mass whilemaintaining the reaction temperature below 45 0., the concentration oi.said cyclopentadiene below 50% by weight, and the proportion 01'catalyst to said cyclopentadiene below 5% by weight, and by stopping thereaction by inactivating said catalyst while benzene-solublepolycyclopentadiene isthe preponderant polymer present in the reactionmass.

10. A process for producing benzene-soluble polycyclopentadiene by thecatalytic polymerization of cyclopentadiene in the substantial absenceof all other compounds polymerizable under the conditions obtaining,comprising mixing with said cyclopentadiene in the presence of anaromatic hydrocarbon solvent of less than 8 carbon atoms to effect saidpolymerization in considerable proportion to polycyclopentadiene ahydrolyzable aluminum chloride-organic solvent complex previously formedby reacting aluminum chloride withan organic solvent capable of reactingwith aluminum chloride to form said hydrolyzable complex; and preventingthe polymerization of said cyclopentadiene from being eiiected largelyto benzene-insoluble polycyclopentadiene by thoroughly agitating therea'ctionmass while maintaining the reactiontemperature below 45 C., theconcentration of said cyclopentadiene below 50% by weight, and theproportion, of catalyst to said cyclopentadiene below 5% by weight, andby stopping the reac- FRANK J. SODAY.

